The _var was chosen because it conflicts with the naming convention in
the rest of the file.
Fixing the error was easier than getting GCC to ignore errors in one
file, or using a pragma to mute the warning.
Introducing a GCC pragma would require disabling C4068 on MSVC (unknown
pragma).
Updating from easylogging++ 9.89 to 9.96.7 turns it from a header only
library to one requiring a source file. It has been added to sources
near the other third party includes in the QMAKE to signify that it
isn't a first party file.
Updating easylogging++ also means that clang-msvc can compile without
any warnings, hence turning on warnings as errors for that compiler as
well, to avoid any regressions.
Vasily